A few years back, my then 4-year old nephew, who is full of questions and not much impulse control, had just played with a sparkler and was watching the ember till it went out. Then, not realizing that it was still hot, says, "Hey, Mommy! I wonder this tastes like!"--and--before she could react--he stuck his tongue out to see. To him it looked like a skinny lollipop.
So, I wouldn't be too quick to blame parents. Kids will do stupid things in moments of curiosity because they're kids. Best thing is not to let them have any, but then they lose out some fun as well.